Steel FDC
FDC is a fine-drawn (cold-drawn, not oil-tempered) plain-carbon spring steel wire of the ASTM A227 class, taking its strength from heavy cold drawing of 0.45–0.85 % C wire.
Reference datasheet — FDC is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the CD condition
FDC tempers and conditions
FDC is supplied in 5 conditions, soft to hard. CD is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | For heavy cold forming, heading or parts that will be hardened and tempered after shaping. | 390 | 640 | 22 | 190 HB | — |
Class I | Use when formability and cost matter more than stress level (larger diameters, gentle bends). | 1,250 | 1,480 | 5 | 44 HRC | 9 % IACS |
CDDefault Cold drawn | Standard stocked condition: patented and hard-drawn wire coiled directly into springs. | 1,360 | 1,600 | 4 | 46 HRC | — |
Cold drawn + stress relieved | Post-coiling low-temperature bake: raises elastic limit, relieves coiling stresses and hydrogen, standard for finished springs. | 1,450 | 1,620 | 3.5 | 47 HRC | 9 % IACS |
Class II | Choose for higher design stress and better set resistance in the same wire size. | 1,490 | 1,750 | 3 | 49 HRC | 9 % IACS |
Supply forms, finishes and certifications
Ways FDC is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
GALV | Hot-dip or electro-galvanized hard-drawn wire | Surface finish |
What is FDC?
FDC is a fine-drawn (cold-drawn, not oil-tempered) plain-carbon spring steel wire of the ASTM A227 class, taking its strength from heavy cold drawing of 0.45–0.85 % C wire. It is the low-cost choice for general-purpose light-duty springs and wire forms and is stocked as CD, stress-relieved CD, CL1, CL2, galvanized and annealed coil. Default values are 1360 MPa yield, 1600 MPa tensile, 4 % elongation and about 46 HRC, with service capped near 120 °C because relaxation rises quickly above that. It has no corrosion resistance and poor weldability; oil-tempered TDC (A229) gives higher and more uniform strength for the same duty. FDC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). FDC has a yield strength of 1,360 MPa (197 ksi) and a tensile strength of 1,600 MPa (232 ksi) — stronger than 96% of steel grades. Elongation at break is 4% and the elastic modulus is 207 GPa (30 Msi).
What is FDC used for?
- light mechanical springs
- clips and retaining rings
- small compression/extension springs
Advantages
- High strength — 1,360 MPa (197 ksi), better than 96% of steel grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 100% of steel grades
- Limited ductility — 4%, worse than 98% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
FDC properties
Typical room-temperature values for FDC-CD; bars are the position among steel grades.
Physical3
FDC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical12
FDC has a yield strength of 1,360 MPa (197 ksi) and a tensile strength of 1,600 MPa (232 ksi) — stronger than 96% of steel grades. Elongation at break is 4% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
FDC is rated for continuous service to 120°C (248 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
FDC conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of FDC takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
FDC's machinability is poor (25/100, worse than 93% of steel grades); weldability poor (20/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. FDC is highlighted; hover a dot for its name, or open the interactive family chart.
Working with FDC
Is FDC easy to machine?
Rarely machined in the hard-drawn state; grind or use carbide for wire-end operations, or machine after annealing.
Can FDC be welded?
Poor weldability — 0.45–0.85 % C gives brittle martensite in the HAZ and destroys the drawn strength; use mechanical joining or resistance-weld with preheat/post-bake only for non-stressed tabs.
Can FDC be formed, bent or molded?
Coils and bends readily on CNC spring formers; allow for large springback, avoid bend radii below about 2× wire diameter, then bake 230–260 °C for 20–30 min to relieve stresses.
FDC chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Ccarbon level selected by wire size / tensile class | 0.45 – 0.85 | 0.65 |
| Mn | 0.3 – 1.3 | 0.7 |
| Si | 0.1 – 0.3 | 0.2 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.02 |
| Fe | balance |
What surface finishes work on FDC?
Supplied oiled or phosphated; zinc/zinc-nickel plating, mechanical galvanizing or powder coating are common — bake within 4 h after electroplating to avoid hydrogen embrittlement; shot peening markedly improves fatigue life.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel FDC in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- A227
How much does FDC cost?
FDC is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
FDC — frequently asked
What is FDC used for?
FDC is typically used for light mechanical springs, clips and retaining rings and small compression/extension springs. In short: lowest-cost spring wire; hard-drawn, not oil-tempered; 120 °C service ceiling.
What is the yield strength of FDC?
FDC has a typical yield strength of 1,360 MPa (197 ksi) and a tensile strength of 1,600 MPa (232 ksi) — stronger than 96% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is FDC easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Rarely machined in the hard-drawn state; grind or use carbide for wire-end operations, or machine after annealing.
Can FDC be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — 0.45–0.85 % C gives brittle martensite in the HAZ and destroys the drawn strength; use mechanical joining or resistance-weld with preheat/post-bake only for non-stressed tabs.
What surface finishes work on FDC?
Supplied oiled or phosphated; zinc/zinc-nickel plating, mechanical galvanizing or powder coating are common — bake within 4 h after electroplating to avoid hydrogen embrittlement; shot peening markedly improves fatigue life.
Can FDC be formed, bent or molded?
Coils and bends readily on CNC spring formers; allow for large springback, avoid bend radii below about 2× wire diameter, then bake 230–260 °C for 20–30 min to relieve stresses.
What is the maximum service temperature of FDC?
FDC is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between FDC-CD and FDC-ANN?
CD is the default condition — standard stocked condition: patented and hard-drawn wire coiled directly into springs. ANN: for heavy cold forming, heading or parts that will be hardened and tempered after shaping. Yield strength is 1,360 MPa in CD versus 390 MPa in ANN.
How much does FDC cost?
FDC is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A227/A227M — Steel Wire, Cold-Drawn for Mechanical Springs — ASTM International (2023)
- JIS G 3521 — Hard drawn steel wire — JSA (2020)
- EN 10270-1 — Steel wire for mechanical springs, patented cold drawn unalloyed — CEN (2017)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- SAE HS-795 Spring Design Manual — SAE International (1996)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.